Presentation on theme: "Sheep Brain Dissection Guide"— Presentation transcript:
1Sheep Brain Dissection Guide GoodLuck!!Laurie Hayes
2To beginGet gloves and a rubber apron or lab coat. Goggles are available if you would like them.Pick up dissection tray, dull probe, pins and labelsObtain a sheep brain and share this with a partner (or 2)Rinse the sheep brain to remove preservative
3Meninges of the BrainBrain is protected by the skull and 3 layers of membranes called meninges
4Observe MeningesExamine the brain to see if there is a tough outer coat…This is the DURA MATER (literally means “tough mother”)Now look for the stringy, web-like ARACHNOID MATER (literally means spider mother) beneath and stuck to the dura mater. The space under the arachnoid, the subarachnoid space, is filled with cerebrospinal fluid and contains blood vessels.Look deeper and see an thin transparent membrane that follows the contour of the ridges (gyri) and valleys (sulci) of the brain. This is the PIA MATER ( means tender mother)
5Questions?? What is the function of the meninges? Describe the following meninges:Dura mater, Arachnoid mater, and Pia materWhat is meningitis?
6Main Brain RegionsIdentify the cerebrum, brain stem) and cerebellum on your brainDraw picture of sheep brain and label structuresCerebrumCerebellumBrain stem
7Questions?? Which part of the brain allows for 1) Balance 2) Breathing 3) Hearing and Vision
8Human vs SheepCompare the various areas of the sheep brain (cerebrum, brain stem, cerebellum) to the human brain.#4. How is it the same and How is it different?Human brain
9Identify Dorsal Structures With the dorsal side up, identify the cerebral hemispheres, gyri, sulci,and longitudinal fissure on your sheep brain
10Questions?? What does the longitudinal fissure divide? What is the difference between gyri and sulci?What is the purpose of the gyri and sulci?
11Lobes of the CerebrumFind the 4 lobes of the brain-frontal, parietal, occipital,and temporalUsing pins label each lobeTeacher check
12Questions???? Name the lobe that functions in a) Hearing b) Vision c) Touchd) Movement
13Corpus CallosumAt the longitudinal fissure, gently separate the two hemispheres and look down between them for the thick band of white fibers. This is the corpus callosumWhat is its function?
14Identify Ventral Structures Place the sheep brain ventral side up.Identify the olfactory bulb, optic nerve, optic chiasmUsing pins label each structure.Draw and label the structures in lab writeup
15Questions??How does the human brain’s olfactory bulb differ from the sheeps?Which is able to smell more odors?Look at the optic chiasma. What happens to the optic nerve (vision) at the optic chiasma?Which side of the occipital lobe (right or left) “sees” for the right eye?
16Brain StemLook at the three parts of the brain stem-the midbrain (cerebral peduncle and mammilary body), pons and medulla oblongataPin and label partsTeacher check
17FunctionMammillary bodies serve as relay stations for reflexes related to sense of SMELLCerebral Peduncle-group of myelinated nerves
18Questions?? Label your diagram with parts of midbrain and brain stem What is the function of the medulla oblongata and pons?Could you survive without them?Why or Why not?
19Identify dorsal structures Carefully pull the cerebellum away from the cerebrum. Don’t break any structures off.Identify the pineal body, superior colliculi, and inferior colliculi.
20Functions-Reflex Centers Inferior Colliculi- movement of head and trunk in response to sound stimuliSuperior Colliculi-movement of eyes, head and neck in response to visual stimuli
21Pineal Gland Produces the hormone melatonin at night Melatonin is the sleep hormone
22Questions??What is the function of the Pineal body?
23Midsagittal Section Obtain a brain the has been cut in half Locate the brain stem parts: the medulla oblongata, the pons, cerebrum, and cerebellum
24CerebellumLook at the cross section of the cerebellum. The inner structure is called the arbor vitae (living tree).Why is this a good name for it?
25Midsagittal SectionLocate the corpus callosum, thalamus,lateral ventricle, fourth ventricle and cerebral aqueduct
26Questions What is the function of the ventricles? The cerebral aquaduct allows for the circulation of the cerebral spinal fluid through the ventricles. What do you think would happen if the duct became blocked?How would that affect brain tissue?
27How does the normal brain compare with the Alzheimer’s brain? How would that explain the memory loss?